Attempts have been made to take radar signals received from the aircraft radar system, convert it to a reflectivity value, and store it in a location in a three-dimensional (3-D) weather buffer relative to the range associated with the radar signal. The 3-D weather buffer is an array of computer memory that includes data that describes a distribution of a parameter within a three-dimensional space (i.e., distribution of weather radar reflectivity). In the other attempts, a signal reflectivity value from a range bin is stored in a large number of three-dimensional buffer storage locations, because the radar signal spreads from its source.
A problem with earlier attempts is that ground clutter contamination of the desired weather signal occurs. Previous attempts have involved avoiding ground clutter contamination by pilot control of radar tilt. This method measures the ground scattering properties and uses this to separate ground from weather.
Therefore, there exists a need to more accurately identify weather information and to remove ground clutter contamination from a weather radar signal or identify ground in a weather radar signal.
The present invention is a method, system, and computer program product for storing weather radar return data into a three-dimensional buffer. The method involves modeling the radar signal scattering properties of space surrounding the radar/aircraft. Present radar measurements are compared to predictions of the measurement using the model. A difference between the present radar measurements and the predictions of the measurement is used to adjust the model.
Distribution of ground surface normalized radar cross section (NRCS) is estimated in a manner similar to weather reflectivity estimation. For the ground, the buffer represents the NRCS distribution in two dimensions to describe the ground surface, rather than the three dimensions to describe three-dimensional weather. Because one of the applications of an airborne radar is to provide a radar ground map, the present invention provides a ground map as an inherent part of the processing.
As will be readily appreciated from the foregoing summary, the invention provides more accurate information for storage in a three-dimensional buffer by performing estimations based on an antenna beam radiation pattern and a radar range weighting function.